Preheat your oven to 350°F (175°C).

Grease a 9×13 inch baking dish thoroughly.

Make the Cake Batter:

In a large mixing bowl, beat together the softened butter and granulated sugar until creamy.

Add the eggs one at a time, mixing well after each addition.

Gradually add in the flour and cocoa powder, mixing until well combined.

Stir in the vanilla extract and fold in the chopped pecans.

Bake:

Pour the batter into the prepared baking dish, spreading it evenly.

Bake in the preheated oven for 25 minutes or until a toothpick inserted into the center comes out clean.

Add the Marshmallows:

Immediately after removing the cake from the oven, sprinkle the mini marshmallows evenly over the top.

Allow the marshmallows to sit and soften for a few minutes, then spread them gently to cover the top of the cake.

Prepare the Icing:

In a medium bowl, mix together the confectioners’ sugar, cocoa powder, and softened butter.

Gradually add the milk, stirring until the icing is smooth and creamy.

Finish the Cake:

Once the cake has cooled slightly, pour the icing over the marshmallow layer, spreading it evenly.

Let the icing set before serving.

Variations and Substitutions:
One of the beauties of Mississippi Mud Cake is its flexibility. Here are some variations and substitutions to tailor this cake to your liking:

Nut Variations:

Swap pecans for walnuts, almonds, or hazelnuts for a different flavor and texture.

For a nut-free version, simply omit the nuts or replace them with additional marshmallows or chocolate chips.

Marshmallow Alternatives:

If you prefer, use marshmallow fluff instead of mini marshmallows. Spread it over the hot cake for a similar effect.

Chocolate Chips:

Add a cup of chocolate chips to the batter for an extra dose of chocolate.

Sprinkle chocolate chips on top of the marshmallows before adding the icing for a gooey, chocolatey topping.